Understanding terbinafine for toenail fungus

In this article:

• Efficacy of terbinafine
• How long does it take to work
• What to avoid
• How to take terbinafine
• The bottom line

In this article

• Efficacy of terbinafine
• How long does it take to work
• What to avoid
• How to take terbinafine
• The bottom line

Terbinafine is a prescription medicine that treats fungal infections of the body (ringworm), feet (athlete’s feet or tinea pedis), fingernails, toenails, scalp (dandruff), and groin (jock itch). It belongs to a group of medications called antifungals. Medical experts recommend terbinafine as the first-line treatment for toenail fungus (also known as onychomycosis or tinea unguium) due to its proven efficacy and effectiveness.

Efficacy of terbinafine for toenail fungus

Terbinafine, known by brand names Laml and Terbinex,  is one of the most effective treatments for toenail fungus. “Terbinafine is highly effective for treating toenail fungus because it has activity against a wide range of dermatophyte (fungal species),” says Kibibi Wanzu, DPM, a board-certified foot and ankle surgeon at Modern Podiatry in Atlanta, Georgia. “Oral terbinafine is particularly effective because it is a systemic medication that works on a cellular level, disrupting the fungal cell membrane function, ultimately leading to fungal cell death.”

According to research, a daily oral dose of 250 milligrams (mg) of the antifungal medicine over 12 or 16 weeks cured dermatophyte toenail onychomycosis, a common nail fungus, in 34 out of 151 patients without the need for a second medical treatment.

A second study followed 120 patients with toenail fungus who received oral terbinafine for 6, 12, and 24 weeks. Out of the 98 patients eligible for evaluation of the effects of terbinafine treatment, 67% were completely cured of the fungal infection by week six, 82% by week 12, and 85% by week 24. Patients need to be aware that toenail onychomycosis infections may come back even when they were previously cured. 

Terbinafine isn’t the only oral treatment for toenail fungus. Itraconazole (Sporanox) is another oral antifungal medication that healthcare providers may prescribe for nail fungus. While it’s been proven that itraconazole can cure toenail fungal infections within three months, terbinafine is slightly more effective. In a previously mentioned study, researchers also found that terbinafine was more effective and had lower relapse rates than itraconazole in treating toenail fungus.

Griseofulvin (Gris-PEG) is another oral medication to treat toenail fungus. An older study found terbinafine to be significantly more effective than griseofulvin, with 42% of patients being completely cured compared to only 2% cured with the latter drug.

The fourth oral medication for toenail fungus is fluconazole (Diflucan). It’s not FDA-approved for toenail fungus, but healthcare providers may prescribe it off-label. However, like itraconazole and griseofulvin, fluconazole has significantly lower cure rates for toenail fungus than terbinafine. A randomized, double-blind study discovered that taking 250 mg of terbinafine daily for 12 weeks was more effective than 150 mg of fluconazole weekly for 12 or 24 weeks, with the first-line drug having higher cure rates at 67% compared to 21% and 32%.

Another potential treatment for toenail fungus is laser treatment. During this treatment, your healthcare provider directs a laser beam and special lights at your toenail to treat the fungus. However, cure rates are significantly lower than those of oral medications, and healthcare providers typically do not use lasers as the first-line treatment for toenail fungus. 

Topical treatments, such as ciclopirox (Penlac), efinaconazole (Jublia), bifonazole (Canespor, Bifon, Mycospor), and tavaborole (Kerydin), are also popular treatments for toenail fungus. But, like the other treatments, they’re not as effective as terbinafine. “In contrast, topical applications to treat nail fungus tend to be less effective because they struggle to penetrate the nail plate deep enough to attack the fungus,” Dr. Wanzu says. 

Other potential treatments for toenail fungus include:

• Nail removal (surgical or nonsurgical)
• Combination therapy (oral and topical medications)

Anne Sharkey, DPM, a board-certified podiatrist and owner of Solely Podiatry in Austin, Texas, notes that while terbinafine is considered one of the gold standard treatments for toenail fungus, the most effective medication ultimately depends on the individual’s specific situation. “Determining what the ‘best’ treatment for toenail fungus is depends on several factors, including the type of fungus present, severity of infection, patient health status, comorbidities, medication, as well as preferences,” she explains. 

How long does it take terbinafine to work for toenail fungus

Dr. Wanzu states that the terbinafine treatment process involves taking one tablet by mouth daily for six to 12 weeks. “Over time, the discoloration and texture of the nail will start to improve, and eventually, starting at the base of the nail near the cuticle, you will notice new healthy nail replacing the infected nail,” she explains. 

She notes that it may take some time to notice physical changes after taking terbinafine. “Patience is key—it can take up to 12-18 months for the new growth to totally replace the infected, damaged toenail.”

According to Dr. Sharkey, several factors can affect the speed of recovery from fungal nail infections while taking terbinafine. These factors include the following: 

• History of trauma to the toenail
• Length of time the fungus was present before starting treatment
• Blood circulation problems due to vascular disease or diabetes
• Nutrition and health status
• Age (nails grow more slowly for older adults)

“Fungal infections of the toenail have a high recurrence rate, so it is essential to complete the entire course of medicine, even if your symptoms start to clear up after a few weeks of therapy,” Dr. Wanzu says. “If you stop taking terbinafine prematurely, there is a high likelihood that your symptoms will return.”

Use the following tips to lower the chances of the fungal infection returning:

• Use treatment exactly as instructed by your healthcare provider or pharmacist.
• Take the medication for as long as prescribed.
• Regularly attend follow-up appointments with your healthcare provider.

What to avoid while taking terbinafine

Like any medication, there are drug interactions and contraindications for terbinafine. 

Below is a list of drugs that are known to interact with terbinafine:

• Caffeine (coffee, soda, and chocolate)
• Cimetidine
• Cyclosporine
• Dextromethorphan
• Fluconazole
• Ketoconazole
• Rifampin
• Pimozide
• Thioridazine 
• Blood pressure medications (diuretics, beta blockers, ACE inhibitors, etc.)
• MAO inhibitors
• Medications for heart rhythm problems (amiodarone, flecainide, propafenone)
• Antidepressants 

Please note that this list doesn’t include all possible drug interactions with terbinafine tablets. Before starting the antifungal treatment, notify your healthcare provider and pharmacist of any medications you’re taking. 

There are also known contraindications or situations where taking terbinafine could be harmful to your health. These include:

• Allergies: If you have a history of allergic reactions to oral terbinafine, Dr. Wanzu advises against using the medication for toenail infections. 
• Alcohol: “Due to the metabolism of the drug by an enzyme that is also responsible for the metabolism of many other drugs, careful consideration of the use of this medication is undertaken,” Dr. Sharkey says. “It is best to abstain or minimize alcohol consumption while using the medication because the liver also metabolizes alcohol.”
• Liver disease: According to Dr. Sharkey, terbinafine treatment is not recommended if liver enzymes are elevated or if liver disease or dysfunction exists. 
• Pregnancy and breastfeeding: “Although terbinafine is considered a pregnancy-safe medication, it is not recommended for use during pregnancy,” Dr. Wanzu explains. “Terbinafine is known to be excreted in breast milk, and therefore its use should be limited to after the conclusion of breastfeeding.” Although not FDA-approved, over-the-counter topical terbinafine hydrochloride has been recommended to treat dermatophyte infections during pregnancy.

It’s important to share your medical history, alcohol consumption, pregnancy, or plan for pregnancy with your healthcare provider so they can ensure that taking terbinafine won’t harm your health or the developing fetus.

If you’ve started taking terbinafine, here are a few steps you can take to lower your risk of drug interactions or contraindications:

• Practice foot hygiene: “Fungus thrives in warm, moist environments; therefore, it is important to maintain good foot hygiene and foot care,” Dr. Wanzu says. “Best practices include maintaining clean, dry feet, wearing breathable socks and shoes, and avoiding walking barefoot in public places.”
• Avoid prolonged exposure to sunlight and artificial light: Terbinafine can make your skin hypersensitive to sunlight and artificial light. Avoid or limit exposure to sunlight and tanning beds and wear protective clothing, sunglasses, hats, and sunscreen.
• Avoid or limit alcohol consumption: To lower your risk of side effects, Dr. Sharkey recommends not consuming alcohol while taking terbinafine.
• Notify your healthcare provider: Tell your healthcare provider about your medical conditions and any current medications, supplements, or herbal products you’re using. Also, let them know if you’re pregnant, planning to become pregnant, or breastfeeding. 

How to take terbinafine safely and effectively 

The typical terbinafine dose for toenail fungus is a 250 mg oral tablet, Dr. Wanzu explains. “The usual dosing for fungal toenails is one tablet once a day, by mouth for 12 weeks,” she adds. “The treatment can be taken at any time of the day and does not typically have to be taken with food.”

If you happen to forget a dose, Dr. Wanzu recommends taking it as soon as you remember, unless it’s nearly time for your next dose. “In this case, skip the missed dose and take your next one at the usual time,” she says. “Then continue your treatment until you have finished the entire course of medication.”

The bottom line

According to medical experts and research studies, terbinafine is the first-line medication for treating fungal infections, with higher cure rates and lower relapse rates than other oral, laser, and topical treatments. It can take up to 12 weeks, or four months, for the oral medication to resolve symptoms of toenail fungus. If you’re experiencing toenail fungus, please consult your healthcare provider for a personalized treatment plan and professional medical advice.